Very difficult. Confronting your bosses at work can be counterproductive however wrong they are.

You could try sending him a written apology with a copy sent to the boss who gave you permission in the first place. Something along the lines of:

Dear Major Smith,

I am sorry that I embarrassed you, my co-workers and the company and have reflected badly on the professionalism of the job.

I am not a transvestite but of Scots/Irish heritage which I am proud of but never-the-less accept that it was not appropriate to wear my kilt at work.

I did discuss this with Mr XXXX and he said it was OK but I should have discussed it with you as my immediate superior.

You may rest assured that it will not happen again.

Your sincerely

Kilt wearing B'stard

If you are going to write such a letter you want it to appear naive rather than sarcastic.

If the owners have any gumption they are going to asking why you are apologizing for something that you should not be apologizing for and why on earth you are mentioning transvestites.

If you are going to go down this route you might want to post the letter on here so that others more divorced from the emotion of the case can just check that you've got the tone OK.